A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to the software and data as described below and in the drawing hereto: Copyright (copyright) 1998, Microsoft Corporation, All Rights Reserved.
This invention relates generally to software installation, and more specifically to automating the installation and cleanup of software applications.
The rapid evolution of personal computer technology continues to produce personal computers that are smaller, cheaper and faster than their predecessors. Where computers once occupied entire rooms, they are now small enough to fit in the palm of the hand, hence the name xe2x80x9cPalm-size PCsxe2x80x9d.
The reduced size of the Palm-size PC means that certain sacrifices need to be made. For example, a typical Palm-size PC does not have fixed or removable disk drives such as hard disk, floppy disk, CD-ROM or DVD-ROM drives, with the persistent storage of a typical Palm-size PC comprising flash memory or volatile memory with a battery refresh. In addition, the amount of RAM in the typical Palm-size PC is also limited, resulting in specialized operating systems capable of running in the resource-limited environment of the Palm-size PC. An example of such an operating system is the Windows CE(trademark) operating system from Microsoft Corporation. Applications running on the Palm-size PC must also be capable of running in the resource limited environment described above. Applications running on the Palm-size PC are typically specialized versions of applications available on the bigger siblings of the Palm-size PC, such as calendar programs, personal information managers, calculators, dictionaries and the like.
In many markets, the Palm-size PC is typically a companion PC to a desktop or other larger PC. Having a desktop PC available allows new or updated application software to be delivered to a Palm-size PC by downloading the software to the Palm-size PC from the desktop PC through a communications link between the two systems.
However, in certain, typically less developed markets, ownership of desktop PCs is not common, and a Palm-size PC may be the only PC that the user has access to. As a result, the ability to deliver software to a Palm-size PC on a Compact Flash or PCMCIA memory card has been developed as an alternative to downloading software from a desktop PC. This mechanism has the advantage that a companion desktop PC is no longer required in order to update or load new software, however several problems remain.
A first problem is that Palm-size PCs do not typically provide an interface allowing a user to discover what software is available on the Compact Flash card. For example, a desktop or larger PC will typically have what is known in the art as a browser. Browsers display the files that reside on the file system of a disk or other memory device and provide the capability for a user to xe2x80x9cbrowsexe2x80x9d through file systems to locate files. Among these files are executable software applications. Because the Palm-size PC has limited memory resources, browsers are not typically provided. Thus, the user has no way of locating any executable application files that may exist on the Compact Flash or PCMCIA memory card.
A second problem is that no xe2x80x9ccleanupxe2x80x9d takes place when the Compact Flash card is removed. An application that has been installed on a Palm-size PC consumes some of the resources of the PC. Typically, these resources include memory to hold the application and its data, display space to display icons and program output from the application. In addition, operating system resources are also consumed in the form of registry entries, process table entries and the like. Because the Palm-size PC has limited resources to begin with, it is important that these resources be released when they are no longer needed. However, there is currently no mechanism provided to detect that these resources can be freed.
The above-described problem is exacerbated when the Compact Flash card is repeatedly inserted and removed. In this case, each insertion of the memory card will cause additional resources to be consumed, which are not freed when the card is removed. Eventually the available resources will be depleted to the point where either the performance of the Palm-size PC is severely degraded or the PC crashes.
A third problem is related to the way that PCs, both Palm-size and desktop, access Compact Flash cards. Typical software distribution media, such as CD-ROM, floppy and hard disk drives, are accessed through a software driver which can determine if the media is present and take appropriate action if it is not. However, Compact Flash cards are accessed differently in some operating systems. For example, in operating systems for resource limited environments, the Compact Flash Card is typically accessed directly by the CPU as if it is part of the main memory of the system. Operating systems for desktop PC environments also are capable of direct access, but do so to a lesser extent. Thus, software on a PC may make direct references to the memory on the Compact Flash card without going through a device driver. If the card is removed while the software is running, these references will be to addresses in memory that no longer exists. This typically causes the application to receive what is known in the art as an exception, and can cause the software to crash. In addition, references to non-existent memory can potentially cause other applications or the operating system itself to crash. While it is possible for an application to attempt to check for the presence of the Compact Flash card with every memory reference, such a check is not 100% reliable, and the impact on the performance of the system makes this solution impractical.
A final issue that must be addressed is the fact that Palm-size PCs from differing manufacturers use differing types of CPUs. For example, CPUs from MIPS, NEC and Hitachi have been used in various Palm-size PCs. Each of these CPUs has their own instruction set, and software applications intended for a particular type of CPU must use the instruction set for the CPU it will be run on. In order for a single Compact Flash memory card to deliver software for a variety of Palm-size PCs, multiple versions of the software must be stored on the card.
Thus, there is a need for a system for automatically cleaning up and releasing resources acquired by software delivered on a Compact Flash memory. There is also a need for a system that installs the software without requiring the use of a browser. Finally, there is a need for such a system that supports multiple hardware environments.
A system and method for automatically cleaning up and releasing resources acquired by a software application is described. The system includes an event monitor that detects when a Compact Flash memory card containing software to be installed has been inserted or removed. Upon insertion of a Compact Flash card into a slot in a Palm-size PC, the event monitor receives an event indicating the insertion, and searches the Compact Flash card for an autorun program, which is invoked to install the software on the card. One aspect of the invention is that the event monitor locates the autorun program by searching in architecture specific directories on the Compact Flash card.
Upon removal of the Compact Flash card, the event monitor receives an event indicating the removal. The event monitor then invokes the autorun program with an uninstall parameter to cause the program to terminate the installed application, and free or release resources acquired during the installation process. Among these resources are registry entries, configuration files, display icons etc.
Because a cleaning program can be automatically invoked, resources can be automatically cleaned up after an application has been installed from a Compact Flash card. The potential for application or system crashes caused by referencing memory on the card when it is no longer present is reduced. In addition, limited resources of the Palm-size PC are freed for use by other applications and programs. Finally, because the installation process is automatically performed when the card is inserted, there is no need for a browser program.